Absolute Coronary Flow Reduction Mediated by Microvascular Resistance in Myocardial Infarction: The FLOVITA Study

Area of Science:

• Cardiology
• Vascular Physiology
• Interventional Cardiology

Background:

• Fractional flow reserve (FFR) assesses epicardial coronary stenosis.
• Microvascular dysfunction post-myocardial infarction (MI) can impact FFR interpretation.
• The FLOVITA study investigated the effect of prior MI on coronary blood flow.

Purpose of the Study:

• To assess the impact of myocardial necrosis on absolute coronary blood flow.
• To evaluate microvascular resistance using pressure wire-based continuous thermodilution.
• To determine factors associated with reduced coronary blood flow after MI.

Main Methods:

• Prospective pilot study of 40 patients (23 with recent anterior ST-elevation MI, 17 controls).
• Coronary physiological assessment of the left anterior descending (LAD) artery.
• Measurement of absolute coronary blood flow and microvascular resistance via continuous thermodilution.

Main Results:

• LAD absolute blood flow was significantly lower in the MI group (0.169 L/min) versus controls (0.215 L/min).
• Infarct size and microvascular resistance were independently associated with reduced flow.
• Increased infarct size and microvascular resistance correlated with decreased LAD flow.

Conclusions:

• MI significantly reduces coronary blood flow, primarily through increased microvascular resistance.
• Microvascular dysfunction is a key factor affecting coronary blood flow post-MI.
• Accounting for microvascular dysfunction is crucial for interpreting post-MI coronary physiology.